One thing I'd like to see covered is sender dependent outgoing mail routing.<p>For example, suppose I have things set up so all outgoing mail from my home goes through my SMTP server. If I send an email with a from address of tzs@mydomain, then the setup in the article is perfect.<p>Suppose, though, I send an email from home with my from address set to tzs@employer, where "employer" is my employer's domain? Assume this email is not to an @employer address [1]. With the setup in the article (and in almost every other similar setup I've seen covered in similar articles) this might run into spam filter issues unless I've convinced my employer to add my SMTP server to their SPF record.<p>The way I want this to be handled is for my SMTP server to see that the mail is from an @employer address, and instead of trying to deliver it directly, relay it through employer's SMTP server.<p>This is similar to the common "smart host" configuration often used when you run an SMTP server at home, but want it to send all outgoing mail through your ISP's SMTP server instead of trying direct delivery. Essentially what I want is a conditional smart host based on the from address.<p>Postfix supports this. In fact, it seems to support it in a couple different ways. I played with it a bit but could not quite get it working.<p>What I'm doing for now, until I find out how to do it right, is only send work email outside of work from my desktop Mac. I took tzs@employer off the list of mail aliases for my mydomain mail account, and created a second account in Apple Mail for @employer. I set the incoming mail server to POP3 on 127.0.0.1 so that it would fail, and set the outgoing server to smtp.employer. It complained for a while that it could not contact the POP3 server, but eventually stopped complaining, and the address in the configuration dialog changed to 0.0.0.0.<p>With that setup Apple Mail sends mail from @employer directly to my employer's SMTP.<p>Sometime recently, after an OS update, that stopped working. It would no longer let me enable an account unless it could successfully talk to the incoming mail server for that account.<p>I did find an ugly workaround for that. I gave it the correct address for employer's POP3 server, and the correct password. Once it was happy, I went to Keychain Access, found the saved password for the POP3 server, and changed it in Keychain Access to something incorrect. Mail then complains that it cannot login to the POP3 server, but that does not cause it to disable the account. Net effect: a send only account in Apple Mail. (It is important to do the password change in Keychain Access, not in Mail, because Mail won't save the change until it sees the new password work).<p>(If that had not worked, I probably would have written a dummy POP3 server that always reports no mail and used that).<p>[1] This happens reasonably often for me, because I have my mail server set up to use fetchmail to fetch my incoming work email and deliver it via procmail. Same for any other SMTP accounts I have. That way I only have to configure mail clients to work with mail server and I get access to all my mail from all of my non-web email accounts.